Machine for automatically timing the immersion of an article into a series of liquids



Oct. 28, 1952 F DAVls r 2,615,421

MACHINE FOR AUTOMATICALLY TIMING THE IMMERSION OF AN ARTICLE INTO A SERIES OF LIQUIDS Filed May 18, 1950 3 Sheets-Sheet l /a 14 1| I rlllllllll I I1 H l T V-f I a 1 A51 45 47 7 1 I l 2 20 l I 50/ 52 L I 62 m /9 1" E: I

29 If 34 v TH; /0

F/g, /nvenfors George F Dav/s E/*nesf J, Ayars fet y Oct. 28, 1952 G. F. DAVIS ETAL 2,615,421

MACHINE FOR AUTOMATICALLY TIMING THE IMMERSION OF AN ARTICLE INTO A SERIES OF LIQUIDS Filed May 18, 1950 3 Sheets-Sheet 2 /n venfors George F Dav/s Ernesf J Aye/rs ,2 )2 @M Affomey G. F. DAVIS ET AL MACHINE FOR AUTOMATICALLY TIMING THE IMMERSION Oct. 28, 1952 OF AN ARTICLE INTO A SERIES OF LIQUIDS 3 Sheets-Sheet 5 Filed May 18, 1950 Fig 4 /n ven fors George F. Dav/s Ernesf J. Ayars A. @M

Afforne y Patented Oct. 28, 1952 MACHINE FOR AUTOMATICALLY TIMING THE IMMERSION OF AN ARTICLE INTO A SERIES OF LIQUIDS George F. Davis, Middleville, and Ernest J Ayars,

Grand Rapids, Mich.

Application May 18, 1950, Serial No. 162,796

9 Claims.

The present invention provides a machine capable of performing a predetermined series of operations in which samples of materials areimmersed in fluid media. These machines find their principal utility in the processing of body tissues by medical laboratory technicians to develop certain characteristics in the tissues in order to aid in the diagnosis and study of disease. Without an automatic machine to perform the operations, the subjecting of samples to various fluid media for a predetermined length of time and under controlled conditions constitutes an extremely tedious and time-consuming task.

Automatic machines for performing these sequential operations are known to the prior art as is indicated in several issued patents. In general,

I these machines have involved a fixed base on which a. series of containers is mounted holding the various fluids to which the samples are to be subjected. The platform supporting the various containers is usually round, and a rotating turret is provided to which suitable sample-holding means are attached. The containers and the holding means are interrelated in such a manner that the rotation of the turret about its axis positions the samples over successive containers during the cycling operations of the machine. The operation of the machine involves the vertical movement of the turret a sufilcient amount to remove the samples from the container with adequate clearance, and the indexing or rotation of the turret to position the sample above the next container. A lowering of the turret completes the series of operations, and a sequence-determining mechanism is used to bring the actuating mechanism into operation and control the timing of the process and the steps of the indexing cycle. The machines provided by the prior art to perform these functions have generally involved a rather elaborate collection of mechanical comin considerable difficulty in the operation of the mechanical skill of the average individual, and

requires the services of a. specialist. It is-the general custom, in fact, for users of the machines to make no attempt to service them themselves but to return the entire device to the factory for readjustment or replacement of worn parts.

In response to the above situation, the present inventors have provided a machine having ,a much more positive action and involving a cycling mechanism of vastly. greater simplicity. The preferred form of this invention includes a fixed tissue-supporting rack attached to a suitable mounting, and a moving container rack capable of vertical movement and rotary indexing. The cycle of operations of such a device includes the lowering of thecontainer rack an amount sumcient to clear the samples from the containers, and the rotation of this rack enough to submit the samples to the next container in order. An elevation of the rack to again submerge the samples in the appropriate containers completes the functional aspects of the cycle. Since it is usual to use a pendulum-type suspension for the tissue samples in supporting them upon the fixed rack, it. follows that any movement of that rack will inevitably induce some degree of swinging or other oscillation. With the tissue-supporting rack remaining fixed, there will be no tendency for the samples to deviate from a fixed position since the engagement of the samples with the containers is preferably in an exclusively vertical direction.

The preferred structure of the present invention involves a fixed base to which a rigid verti cal column member is firmly attached. The tissue-supporting rack is secured to the upper portion of this column. A movable container-supporting rack is rotatably mounted upon the central column, and is maintained in a generally horizontal plane through being attached securely to a sleeve surrounding the column. With this arrangement, it is clear that the container rack is capable of rotary movement around the axis of the column and also axial movement along.

the column. e

The stabilizing sleeve provided for the container rack is preferably fitted with a pulley wheel or sprocket depending upon whether the indexing mechanism operates through the action of .a chain or a belt. A fluid-driven motor is attached to a second member carried by the column, also mounted upon a suitable sleeve, but which is capable only of axial movement. The position of of its sleeve with the toner the member supporting the fluid motor. A suitable thrust bearing at this point transfers the various loads involved and permits relative rotation between the motor support and the container rack. The fluid motor is provided with a pulley or sprocket in the same plane as that of the pulley attachedto the container rack sleeve, and rotation of the motor induces relative rotation between the container rack and the fixed portions of the machine.

The elevation and lowering of the container rack are accomplished by means of a hydraulic jack or an equivalent mechanism operating against the motor platform. As the motor platform is elevated, forces are transmitted through the aforementioned thrust bearing, and the container rack is moved accordingly. The motor platform or support preferably engages a fixed rod disposed parallel to the central column, and this engagement acts in the manner of a keyway to prevent rotation of the motor support relative to the column.

The use of a fluid motor and a fluid-operating elevating system makes possible a single hydraulic circuit under the control of a series of electrically-operated valves. The use of a liquid rather than a gaseous fluid medium is much to be preferred due to the relative freedom of the liquid from changes in volumewith changes in pressure. A gaseous medium has a tendency to develop a jerky motion in the cycling system as the gas pressure reaches a point where the friction of themechanism is just about to be overcome. The hydraulic circuit includes a suitable reservoir. a pump, and preferably an electric motor capable of handling whatever type of current is provided in the locality where the. machine is to be used. Preferably, a single valve mechanism is adapted to control the inlet and outlet lines of the fluid motor in such a manner that both are open at the same instant and both can be closed to prevent any movement of fluid through the motor whatever.

The preferred form of the elevating mechanism comprises a conventional hydraulic jack mechanism. To control the jack mechanism, a pair of valves, or their equivalent, is required. The operation of the elevating mechanism will make it clear why the double valve system is necessary. It is first required that the lifting mechanism lower the beaker rack in order to clear the tissue samples from the containers. This is accomplished by permitting the exhaust of the fluid contained in the jack mechanism underneath the piston. With most modifications of the mechanism, it is not necessary to apply pressure on the upper side of the cylinder in order to force the piston down due to the fact that the weight of the components is usually sufficient to accomplish this purpose. If the weight in a particular machine is not sufficient, it is very simple to apply a relatively small and constant pressure above the piston to assure the movement of the mechanism in the required fashion. As the exhaust of the liquid underneath the piston proceeds, the container rack moves axially along the column in a downward direction. When the limit of this movement is reached, the exhaust line is closed by the valve associated therewith; and both exhaust and inlet are securely held in this closed position during the indexing or rotary movement of the beaker rack. When the rack has reached its new position, the valve controlling the pressure inlet to the elevating mechanism is opened and the beaker rack is lifted causing the immersion of the samples in the appropriate containers.

4 When the rack has reached its proper upward limit of travel, both pressure and exhaust lines are again securely closed resulting in the holding of the container rack in the proper position until the next cycle is begun.

The determination of the sequence and timing of the various operations outlined above is preferably performed by electrical apparatus having two general aspects: (a) a clock-operated device establishing the length of time the tissue samples are to be submerged in the various fluid media, and (b) the sequence-determining circuit establishing the operation of the various hydraulic valves controlling the movements of the jack mechanism and the indexing system. The preferred form of the timing device includes a series of adjustable controls having the function of establishing the length of time for each successive operation, each of the controls being associated with a particular immersion cycle. A second portion of the timing device determines which of the selective controls is in operation at a particular moment. The actual control of the sequence of operations during the changing cycle is determined by a series of switches, the position of which are controlled by the position of the mechanical components of the device.

A rotary cam plate moves with the container rack and cooperates with switching means to con trol the indexing operations. A generally annular actuator moves vertically with the container rack, and the vertical position of this actuator acting in cooperation with another series of switches serves to control the vertical positioning system. The timing device outlined above serves to energize the sequence-determining system, and the complete cycle of operations is then performed with the machine repositionin'g the tissue samples in the appropriate containers for the proper length of time determined for the next immersion operation. The sequence determining system is arranged so that the supply of electrical energy is maintained until the cycle is completed regardless of the condition of the clock-operated system once the cycle has been initiated.

The several features of the present invention will be analyzed in detail by a discussion of the particular embodiments illustrated in the accompanying drawings. In these drawings:

Figure 1 is a section taken in elevation through a machine embodying the present invention, with the container rack in the down" position.

Figure 2 shows a broken away portion on a plan view of the container rack. v

Figure 3 is a schematic diagram of the hydraulic circuit embodied in the device shown in Figiu'e 1.

Figure 4 is a schematic arrangement showing the relationship of the electrical switches and the mechanical actuators comprising the sequencedetermining system.

Figure 5 is a schematic diagram showing the clock-operated system for determinin the length of time of the various immersion periods.

Referring to Figure l, a. tissue-processing machine is shown comprising a base 13, a fixed vertical column ii and a housing 12 rigidly attached to the base i8. At the upper extremity of the column H, a rack I3 is provided from which are suspended a series of tissue-containing baskets it. These baskets are preferably of loose mesh or screen and are of such a na-ure as to provide ready circulation of the fluid media present in the containers l5. T.hc baskets M are preferably suspended from the rack 38 in'such' a'manner that they may be readily removed; and may be merely hung in place through a conventional hook-and-eye arrangement.

A'container rack I6 is arranged coaxially with respect to the column II, and is firmly attached to the sleeve I'I adapted to slide axially along the column II and to rotate freely around it. The purpose of thesleeve I! is to maintain the perpendicular alignment of the tissue rack I6 and the column II The vertical position of the sleeve I1 and the rack IIi is controlled by the engage ment of the thrust bearing at the lower end of the sleeve IT with the vertically movablecarrier I8. The principal function of the carrier I8 is to provide a mounting for the hydraulic motor means indicated at I9 havingthe function of inducing rotary motion to the sleeve I1 and the container rack I-6. A pulley 29 is firmly attached to the sleeve I'I in order to transmit torque from the motor I9 to the sleeve by means of the belt The carrier I8 is restricted to vertical movement alon the column I I due to the engagement of the fixed rod 22 with a suitable aperture in the carrier l8. The vertical position of the carrier is controlled by the hydraulic jack system 23. The sleeve 24 is firmly attached to the carrier I8 "and has the function of maintaining the carrier in a horizontal position. With the mechanism arranged as outlined above, the extension of the jack system 23 causes the upward vertical movement of the push rod 25 resulting in the elevation .of the carrier I8, and likewise causing vertical movement of the sleeve I1 and the container rack The essentials of the hydraulic mechanism are generally indicated in the lower portion of the view shown in Figure 1. These units include the electric motor 26, the pump 21, the reservoir 28,

and the valve unit designated at 29. The positioning of the container rack by these components is rendered positive by the action of the locking peg 30 mounted at the upper portion of the column II on the arm 3I. The arm 3I is mounted upon a suitable collar, and the vertical and angular alignment of the arm is maintained in fixed position by the pin 32. A series, of apertures 33 is positioned for each angular position of the container rack I6 about the axis of the column II. The lower portion of the pin 30 is tapered so as to bring the apertures 33 and the .pin 30 into alignment as the container rack 'moves upwardly. With the firm engagement of the pin 30 and one of the apertures 33, no leakage or other misfunction in the hydraulic sys tem will suflice to change the relative position of the container rack and. the baskets durin the immersion period.

Referring to Figure 3, the inter-relation of the various components collected at the lower portion of Figure l is illustrated. The hydraulic jack 'unit 23 is provided with the inlet conduit 34 con- 'trolled by the valve 35, and the outlet conduit 36 dicated at M.

y The by-pass valve 42 is provided in the high pressure line .43 of the hydraulic circuit and has the function of setting an upper limit to the pres- .sure supplied to the system. Electrical energy is furnished to the motor 26 by means of suitable leads 44.-

The control of the solenoid-operated valves 35, 31 and 4| is provided by the switch circuits indicated schematically in Figure 4. The sleeve I1 carrying the container rack I6 is provided with the cam plate 45. This plate moves angularly and vertically with the container rack. A switch unit generally designated at 46 is mounted upon a fixed member in the device, and is preferably attached to a suitable mounting plate 41 on top of the guide rod 22 (refer to Figure l). A second switch 48 is mounted uponthe plate 41, and both switch 46 and switch 48 are actuated by projections upon the cam plate 45. A generally annular actuating projection 49 is firmly attached to a ring 50 mounted upon the container rack I6. The ring 50 will therefore move vertically with the container rack, and the annular nature of the projection 49 will result in a uniform surface for the actuation of the switches 51, 52, and 53 regardless of the angular position of the container rack about the axis of the coluinn II. This arrangement makes the last mentioned switches responsive solely to the vertical position of the container rack. In Figure 4, the ring 50 is in the lower position corresponding to the attitude of the machineshown in Figure l. The containers are disengaged from the sample baskets during this phase of the cycle. The dotted line position of the projection 49 in Figure 4 indicates the position with the samples immersed in the material contained in thecontainers I5. v

-When a changing cycle is initiated by the clock-operated device to be discussed hereinafter, the relay generally designated at 54 is closed, resulting in the completion of the circuit between the points 55 and 56, and also between 51- and 58. The completion of this'circuit supplies electrical energy to the motor 26, and begins the generation of the necessary fluid pressure to operate the hydraulic system. At this moment, the switch 46 will be in the position shown, in which a circuit is established from the line 59 to the line 60, resulting in energizing the solenoid valve 31 and thereby causing the lowering of the container rack I6 and the cam plate 45. As soon as the lowering has begun, the annular projection 49 will move downwardly and permit the switch 5I to close resulting in maintaining the supply of electrical energy to the system regardless of the position of the clock-operated device. The closing of the switch 5| applies the voltage across the motor 26 to the relay 54, since the circuit between points 55 and 56, and also between 51 and 58, is als'oclosed at that time. h

The downward movement of the cam plate 45 brings it in a plane opposite the switches carried by the bracket 41. It is this attitude which is represented in Fig. 4. When the extreme downward movement has been reached, the pro- .iection 49 closes the switch 53, and thereby establishes a circuit through the switch 48 (now in closed position) energizing the solenoid valve 4I and causing the rotation of the fluid motor I9. The rotation of the motor I9 continues until the cam plate 45 has revolved sufficiently to bring one of the actuating projections into engagement with the operating arm of the switch 48. Such action breaks the contact previously maintained by the switch 48, and terminates the operation of the fluid motor I9. At approximately the same. moment, the. switch. .46.. is actuated by a similar projection upon the cam 45 establishing a circuit between the line 59 and the line Bl. The establishment of this circuit energizes the solenoid valve 35 and thereby admits pressure to the jack mechanism 23 causing the container rack to be elevated to the level indicated in dotted lines on Figure 4. As the extreme upper position is reached, the annular projection 49 opens the switch and thereby terminates the operation of the device, since the relay 54 is by this time no longer energized by the clockoperated mechanism. As the sleeve l7 moves upward to its extreme position, the reset plate 62 cooperates with the operating arms of the switches 46 and 48, and restores them to the position shown in Figure 4. This restoring is accomplished by the engagement of the slanted surface 63 with the operating arms during the exclusively vertical movement of the plate 62.

The delivery of the initial signal to the sequence system noted in Figure 4 is provided by the clock-operated mechanism schematically illustrated in Figure 5. A shaft 64 is driven preferably by an electric clock motor 64a, or any equivalent device establishing a uniform or predetermined rate of rotation. An actuator 65 is carried by the shaft 64, and acts upon the switches normally open 66, 61, B8, and 69. These switches are spaced around the shaft 64 and are preferably mounted upon a suitable plate to establish their position.

A series of adjustable units 10 is provided that has the function of determining the length of time for each of a series of immersion operations. open contacts and a contacting arm, the contacts being associated with one of the switches 6'6, 61, 68, or 89. The placing of the contacting arm of one of the units 10 in a particular position will thereby establish a connection between the arm and one of the aforementioned switches. Each of the contacting arms of the unit 10 is associated with a particular contact of the stepby-step contactors H. The contacting arm 12 of this unit serves to connect a selected one of the contacting arms of the units 10 with the line represented by the letter a. With this arrangement, the time between the completion of circuits between the lines a and 0 will be be determined by the length of time required for the actuator 65 to rotate until a particular one of the switches 66, 61, 68, or 69 is closed which is connected through the unit H with the line a. The actuator 65 will continue to rotate operating each of these switches until the circuit is completed, and the length of time required to pass from its starting positionto the active switch will determine the length of time of each successive immersion period. The setting of the units 70 operates to select which of the switches surrounding the actuator 65 is to be the active one, and therefore the manual setting of the units H3 selecting one of these switches will in effect determine the length of time for the immersion period controlled by that particular one of the units 16. The operation of the step-by-step selector unit H merely determines which of the time-selection devices is to control the circuit for a particular immersion period. Each time the circuit is completed through the switches, the adjustable units 10, and the selector unit 'H, a circuit is also completed from the line 13 through the advancing mechanism generally indicated at 14. The operationof the advancing mechanism .14 automati- Each unit comprises a series of normally cally moves the contacting arm 12 on to, the next contact. The clock mechanism will then continue to run until the actuator 65 rotates to whatever switch has been selected by the next unit 10 according to the connections with contacts around the unit H. In this manner it is possible to arrange a definite series of immersion periods, each one having a characteristic duration. The completion of the circuit between the lines a and c by the mechanism outlined above serves to energize the coil of the relay 54 shown in Figure 4. It is preferable that the advancing mechanism 14 shall operate upon the. release of the supply of electrical energy fed to it. This arrangement can be provided by the usual solenoid and spring system in which the operation of solenoid places suflicient energy in the spring to operate a ratchet upon the release of the solenoid. If the stepping mechanism advances the arm 72 upon the first instant of the completion of the circuit through the lines 13, the stepping mechanism will break the circuit before the annular projection 49 moves down to permit the holding switch to maintain the supply of electrical energy to the sequence mechanism shown in Figure 4.

It is preferable that the operation of the clock be halted during the cycling operations for greater accuracy in timing the immersion periods. The switch 52 is positioned for operation by the projection 49, and stops the clock during the time the samples are out of the containers.

The particular embodiments which have been illustrated in the accompanying drawings and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims it is the intent of the inventors to claim the entire invention to which they are entitled in View of the prior art.

We claim: 7

1. An immersion processing machine comprising: container-support means mounted for rotation in a substantially horizontal plane; positioning means for establishing the position of said container-support means in a vertical direction, said positioning means including a hydraulic jack; indexing means for angularly advancing said container-support means about its axis, said indexing means including hydraulic actuating means; hydraulic pressure-generating means; valve means disposed to control the flow of liquid to and from said pressure-generating means, jack and actuating means; sequencedetermining means adapted to operate said valve means according to a particular cycle of operation; and material support means-disposed to position said material for immersion in con tainers positioned by said indexing and container-support means.

2. An immersion processing machine comprising: container-support means mounted for rotation in a substantially horizontal plane; positioning means for establishing the position of said container-support means in a vertical direction, said positioning means including a hydraulic jack; indexing means for angularly advancing said container-support means about its axis, said indexing means including rotating hydraulic motor means; hydraulic pressure-generating means; valve means disposed to control the flow of liquid to and from said pressure-generating means, jack and motor means; sequence-determining means adapted to actuate said valve means according to a particular cycle of operation; and material support means disposed to position said material for immersion in containers'positioned by said indexing and containersupport means. I

3. An immersion processing machine comprising: means forming a fixed vertical column; first carrier means slideably and rotatably mounted on said column means; container-support means mounted on said first carrier means for rotation in a substantially horizontal plane; second carrier means slideably and non-rotatably mounted on said column means; positioning means for establishing the vertical position of said first and second carrier means, said positioning means including a hydraulic jack; indexing means for angularly advancing said container-support means about its axis, said indexing, means including rotating hydraulic motor means mounted on said second carrier means; hydraulic pressure-generating means; valve means disposed to control the flow of liquid to and from said pressure-generating means, jack and motor means; sequence-determining means adapted to actuate said valve means according to a particular cycle of operation; and material support means mounted on said column means and disposed to position said material for immersion in containers positioned by said indexing and container-support means.

4. An immersion processing machine comprising: means forming a fixed vertical column; first carrier means slideably and rotatably mounted on said column means; containersupport means mounted on said first carrier means; second carrier means slideably and nonrotatably mounted on said column means below said first carrier means; positioning means for establishing the vertical position of said first and second carrier means; said positioning means including a hydraulic jack; indexing means for angularly advancing said container-support means about its axis, said indexing means including rotating hydraulic motor means mounted on said second carrier means; hydraulic pressure-generating means; valve means disposed to control the flow of liquid to and from said pressure-generating means, jack and motor means; sequence-determining means adapted to actuate said valve means according to a particular cycle of operation; and material support means mounted on said column means and disposed to position said material for immersion in containers positioned by said indexing and containersupport means.

5. An immersion processing machine comprising: means forming a fixed vertical column; first carrier means slideably and rotatably mounted on said column means; container-support means mounted on said first carrier means; second carrier means slideably and non-rotatably mounted on said column means below said first carrier means; thrust-bearing means disposed between said first and second carrier means; positioning means for establishing the vertical position of said first and second carrier means, said positioning means including a hydraulic jack; indexing means for angularly advancing said containersupport means about its axis, said indexing means including rotating hydraulic motor means mounted on said second carrier means; hydraulic pressure-generating means; valve means disposed to control the fiow of liquid to and from said pressure-generating means, jack and motor means; sequence-determining means adapted to actuate said valve means according to a particular cycle of operation; and material support means mounted on said column means and dis posed to position said material for immersion in containers positioned by said indexing and con tainer-support means 6. Control means comprising clock means adapted to drive a shaft at a predetermined rate of rotation; electric. switch means having operating means positioned about the axis ofsaid shaft; actuating means driven by said shaft and adapted to cooperate with said operating means;

first circuit selecting means comprising at least one unit including a plurality of contacts and an adjustable contacting arm; second circuit selecting means comprising a plurality of contacts, a contacting arm, and electrically-operated stepby-step indexing means; firstcircuit' means associating aterminal of each of the switches comprising said switch meanswith a contact on each unit of said first selecting means; second circuit means associating each contact of said second selecting means with the contacting arm of a particular unit of said first selecting means; third circuit means associating the contacting arm of said second selecting means and the opposite terminals of said switches from those occupied by said first circuit means said third circuit means including the controlled load and a source of electrical energy; and fourth circuit means associating said indexing means and switch means so as to energize said indexing means on actuation of any of said switches.

7 An immersion processing machine comprising: container-support means mounted for rotation in a substantially horizontal plane; positioning means for establishing the position of said container-support means in a vertical direction, said positioning means including a jack; indexing means for angularly advancing said container-support means about its axis, said indexing means including motor means; electrical relay means; clock-operated control means adapted to control said relay; switch means connected to control said jack and motor means, said switch means being responsive to various positions of said container support means in sequence; electrical circuit means operatively associating the load side of said relay, said switches, and a source of electrical energy; and material support means disposed to position said material for immersion in containers positioned by said indexing and container-support means.

8. An immersion processing machine comprising: container-support means mounted for rotation in a substantially horizontal plane; positioning means for establishing the position of said container-support means in a vertical direction, said positioning means including a hydraulic jack; indexing means for angularly advancing said container-support means about its axis, said indexing means including hydraulic motor means; hydraulic pressure-generating means; electrically-operated valve means disposed to control the flow of liquid to and from said pressure-generating means, jack and motor means; electrical relay means; clock-operated control means adapted to control said relay; switch means connected to control said electrically operated valve means; said switch means being responsive to various positions of said container support means in sequence; electrical circuit means operatively associating the load side of said relay, said switches, and a source of electrical energy; and material support means disposed to position said material for immersion in containers positioned by said indexing and con-- tamer-support means.

9. An immersion processing machine comprising: container-support means mounted for rotation in a substantially horizontal plane; positioning means for establishing the position of said container-support means in a vertical direction, said positioning means including a jack; indexing means for angularly advancing said contamer-support means about its axis, said indexing means including motor means; electrical relay means; clock-operated control means and adapted to control said relay; first switch means connected to control said jack and motor means, said first switch means being responsive to various positions of said container support means in sequence; second switch means, said second switch means adapted to control said clock means and having an operating member responsive to the position of said container support means; electrical circuit means operatively asso- 12 ciating the load side of said relay, said switches, and a source of electrical energy; and material support means disposed to position said material for immersion in containers positioned by said indexing and container-support means. GEORGE F. DAVIS. ERNEST J. AYARS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,014,282 Beausejour et a1. Jan. 9, 1912 1,943,185 Neville Jan. 9, 1934 2,154,994 Prescott Apr, 18, 1939 2,157,875 Weiskopf May 9, 1939 

